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        <a href="../.." >数值</a>
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                                <h1 id="&#x6570;&#x503C;">&#x6570;&#x503C;</h1>
<h2 id="&#x6982;&#x8FF0;">&#x6982;&#x8FF0;</h2>
<h3 id="&#x6574;&#x6570;&#x548C;&#x6D6E;&#x70B9;&#x6570;">&#x6574;&#x6570;&#x548C;&#x6D6E;&#x70B9;&#x6570;</h3>
<p>JavaScript &#x5185;&#x90E8;&#xFF0C;&#x6240;&#x6709;&#x6570;&#x5B57;&#x90FD;&#x662F;&#x4EE5;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x5F62;&#x5F0F;&#x50A8;&#x5B58;&#xFF0C;&#x5373;&#x4F7F;&#x6574;&#x6570;&#x4E5F;&#x662F;&#x5982;&#x6B64;&#x3002;&#x6240;&#x4EE5;&#xFF0C;<code>1</code>&#x4E0E;<code>1.0</code>&#x662F;&#x76F8;&#x540C;&#x7684;&#xFF0C;&#x662F;&#x540C;&#x4E00;&#x4E2A;&#x6570;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">1</span> === <span class="hljs-number">1.0</span> <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x8FD9;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;JavaScript &#x8BED;&#x8A00;&#x7684;&#x5E95;&#x5C42;&#x6839;&#x672C;&#x6CA1;&#x6709;&#x6574;&#x6570;&#xFF0C;&#x6240;&#x6709;&#x6570;&#x5B57;&#x90FD;&#x662F;&#x5C0F;&#x6570;&#xFF08;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#xFF09;&#x3002;&#x5BB9;&#x6613;&#x9020;&#x6210;&#x6DF7;&#x6DC6;&#x7684;&#x662F;&#xFF0C;&#x67D0;&#x4E9B;&#x8FD0;&#x7B97;&#x53EA;&#x6709;&#x6574;&#x6570;&#x624D;&#x80FD;&#x5B8C;&#x6210;&#xFF0C;&#x6B64;&#x65F6; JavaScript &#x4F1A;&#x81EA;&#x52A8;&#x628A;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#xFF0C;&#x8F6C;&#x6210;32&#x4F4D;&#x6574;&#x6570;&#xFF0C;&#x7136;&#x540E;&#x518D;&#x8FDB;&#x884C;&#x8FD0;&#x7B97;&#xFF0C;&#x53C2;&#x89C1;&#x300A;&#x8FD0;&#x7B97;&#x7B26;&#x300B;&#x4E00;&#x7AE0;&#x7684;&#x201C;&#x4F4D;&#x8FD0;&#x7B97;&#x201D;&#x90E8;&#x5206;&#x3002;</p>
<p>&#x7531;&#x4E8E;&#x6D6E;&#x70B9;&#x6570;&#x4E0D;&#x662F;&#x7CBE;&#x786E;&#x7684;&#x503C;&#xFF0C;&#x6240;&#x4EE5;&#x6D89;&#x53CA;&#x5C0F;&#x6570;&#x7684;&#x6BD4;&#x8F83;&#x548C;&#x8FD0;&#x7B97;&#x8981;&#x7279;&#x522B;&#x5C0F;&#x5FC3;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">0.1</span> + <span class="hljs-number">0.2</span> === <span class="hljs-number">0.3</span>
<span class="hljs-comment">// false</span>

<span class="hljs-number">0.3</span> / <span class="hljs-number">0.1</span>
<span class="hljs-comment">// 2.9999999999999996</span>

(<span class="hljs-number">0.3</span> - <span class="hljs-number">0.2</span>) === (<span class="hljs-number">0.2</span> - <span class="hljs-number">0.1</span>)
<span class="hljs-comment">// false</span>
</code></pre>
<h3 id="&#x6570;&#x503C;&#x7CBE;&#x5EA6;">&#x6570;&#x503C;&#x7CBE;&#x5EA6;</h3>
<p>&#x6839;&#x636E;&#x56FD;&#x9645;&#x6807;&#x51C6; IEEE 754&#xFF0C;JavaScript &#x6D6E;&#x70B9;&#x6570;&#x7684;64&#x4E2A;&#x4E8C;&#x8FDB;&#x5236;&#x4F4D;&#xFF0C;&#x4ECE;&#x6700;&#x5DE6;&#x8FB9;&#x5F00;&#x59CB;&#xFF0C;&#x662F;&#x8FD9;&#x6837;&#x7EC4;&#x6210;&#x7684;&#x3002;</p>
<ul>
<li>&#x7B2C;1&#x4F4D;&#xFF1A;&#x7B26;&#x53F7;&#x4F4D;&#xFF0C;<code>0</code>&#x8868;&#x793A;&#x6B63;&#x6570;&#xFF0C;<code>1</code>&#x8868;&#x793A;&#x8D1F;&#x6570;</li>
<li>&#x7B2C;2&#x4F4D;&#x5230;&#x7B2C;12&#x4F4D;&#xFF08;&#x5171;11&#x4F4D;&#xFF09;&#xFF1A;&#x6307;&#x6570;&#x90E8;&#x5206;</li>
<li>&#x7B2C;13&#x4F4D;&#x5230;&#x7B2C;64&#x4F4D;&#xFF08;&#x5171;52&#x4F4D;&#xFF09;&#xFF1A;&#x5C0F;&#x6570;&#x90E8;&#x5206;&#xFF08;&#x5373;&#x6709;&#x6548;&#x6570;&#x5B57;&#xFF09;</li>
</ul>
<p>&#x7B26;&#x53F7;&#x4F4D;&#x51B3;&#x5B9A;&#x4E86;&#x4E00;&#x4E2A;&#x6570;&#x7684;&#x6B63;&#x8D1F;&#xFF0C;&#x6307;&#x6570;&#x90E8;&#x5206;&#x51B3;&#x5B9A;&#x4E86;&#x6570;&#x503C;&#x7684;&#x5927;&#x5C0F;&#xFF0C;&#x5C0F;&#x6570;&#x90E8;&#x5206;&#x51B3;&#x5B9A;&#x4E86;&#x6570;&#x503C;&#x7684;&#x7CBE;&#x5EA6;&#x3002;</p>
<p>&#x6307;&#x6570;&#x90E8;&#x5206;&#x4E00;&#x5171;&#x6709;11&#x4E2A;&#x4E8C;&#x8FDB;&#x5236;&#x4F4D;&#xFF0C;&#x56E0;&#x6B64;&#x5927;&#x5C0F;&#x8303;&#x56F4;&#x5C31;&#x662F;0&#x5230;2047&#x3002;IEEE 754 &#x89C4;&#x5B9A;&#xFF0C;&#x5982;&#x679C;&#x6307;&#x6570;&#x90E8;&#x5206;&#x7684;&#x503C;&#x5728;0&#x5230;2047&#x4E4B;&#x95F4;&#xFF08;&#x4E0D;&#x542B;&#x4E24;&#x4E2A;&#x7AEF;&#x70B9;&#xFF09;&#xFF0C;&#x90A3;&#x4E48;&#x6709;&#x6548;&#x6570;&#x5B57;&#x7684;&#x7B2C;&#x4E00;&#x4F4D;&#x9ED8;&#x8BA4;&#x603B;&#x662F;1&#xFF0C;&#x4E0D;&#x4FDD;&#x5B58;&#x5728;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x4E4B;&#x4E2D;&#x3002;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;&#x6709;&#x6548;&#x6570;&#x5B57;&#x8FD9;&#x65F6;&#x603B;&#x662F;<code>1.xx...xx</code>&#x7684;&#x5F62;&#x5F0F;&#xFF0C;&#x5176;&#x4E2D;<code>xx..xx</code>&#x7684;&#x90E8;&#x5206;&#x4FDD;&#x5B58;&#x5728;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x4E4B;&#x4E2D;&#xFF0C;&#x6700;&#x957F;&#x53EF;&#x80FD;&#x4E3A;52&#x4F4D;&#x3002;&#x56E0;&#x6B64;&#xFF0C;JavaScript &#x63D0;&#x4F9B;&#x7684;&#x6709;&#x6548;&#x6570;&#x5B57;&#x6700;&#x957F;&#x4E3A;53&#x4E2A;&#x4E8C;&#x8FDB;&#x5236;&#x4F4D;&#x3002;</p>
<pre><code>(-1)^&#x7B26;&#x53F7;&#x4F4D; * 1.xx...xx * 2^&#x6307;&#x6570;&#x90E8;&#x5206;
</code></pre><p>&#x4E0A;&#x9762;&#x516C;&#x5F0F;&#x662F;&#x6B63;&#x5E38;&#x60C5;&#x51B5;&#x4E0B;&#xFF08;&#x6307;&#x6570;&#x90E8;&#x5206;&#x5728;0&#x5230;2047&#x4E4B;&#x95F4;&#xFF09;&#xFF0C;&#x4E00;&#x4E2A;&#x6570;&#x5728; JavaScript &#x5185;&#x90E8;&#x5B9E;&#x9645;&#x7684;&#x8868;&#x793A;&#x5F62;&#x5F0F;&#x3002;</p>
<p>&#x7CBE;&#x5EA6;&#x6700;&#x591A;&#x53EA;&#x80FD;&#x5230;53&#x4E2A;&#x4E8C;&#x8FDB;&#x5236;&#x4F4D;&#xFF0C;&#x8FD9;&#x610F;&#x5473;&#x7740;&#xFF0C;&#x7EDD;&#x5BF9;&#x503C;&#x5C0F;&#x4E8E;2&#x7684;53&#x6B21;&#x65B9;&#x7684;&#x6574;&#x6570;&#xFF0C;&#x5373;-2<sup>53</sup>&#x5230;2<sup>53</sup>&#xFF0C;&#x90FD;&#x53EF;&#x4EE5;&#x7CBE;&#x786E;&#x8868;&#x793A;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>)
<span class="hljs-comment">// 9007199254740992</span>

<span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>) + <span class="hljs-number">1</span>
<span class="hljs-comment">// 9007199254740992</span>

<span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>) + <span class="hljs-number">2</span>
<span class="hljs-comment">// 9007199254740994</span>

<span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>) + <span class="hljs-number">3</span>
<span class="hljs-comment">// 9007199254740996</span>

<span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>) + <span class="hljs-number">4</span>
<span class="hljs-comment">// 9007199254740996</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5927;&#x4E8E;2&#x7684;53&#x6B21;&#x65B9;&#x4EE5;&#x540E;&#xFF0C;&#x6574;&#x6570;&#x8FD0;&#x7B97;&#x7684;&#x7ED3;&#x679C;&#x5F00;&#x59CB;&#x51FA;&#x73B0;&#x9519;&#x8BEF;&#x3002;&#x6240;&#x4EE5;&#xFF0C;&#x5927;&#x4E8E;2&#x7684;53&#x6B21;&#x65B9;&#x7684;&#x6570;&#x503C;&#xFF0C;&#x90FD;&#x65E0;&#x6CD5;&#x4FDD;&#x6301;&#x7CBE;&#x5EA6;&#x3002;&#x7531;&#x4E8E;2&#x7684;53&#x6B21;&#x65B9;&#x662F;&#x4E00;&#x4E2A;16&#x4F4D;&#x7684;&#x5341;&#x8FDB;&#x5236;&#x6570;&#x503C;&#xFF0C;&#x6240;&#x4EE5;&#x7B80;&#x5355;&#x7684;&#x6CD5;&#x5219;&#x5C31;&#x662F;&#xFF0C;JavaScript &#x5BF9;15&#x4F4D;&#x7684;&#x5341;&#x8FDB;&#x5236;&#x6570;&#x90FD;&#x53EF;&#x4EE5;&#x7CBE;&#x786E;&#x5904;&#x7406;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>)
<span class="hljs-comment">// 9007199254740992</span>

<span class="hljs-comment">// &#x591A;&#x51FA;&#x7684;&#x4E09;&#x4E2A;&#x6709;&#x6548;&#x6570;&#x5B57;&#xFF0C;&#x5C06;&#x65E0;&#x6CD5;&#x4FDD;&#x5B58;</span>
<span class="hljs-number">9007199254740992111</span>
<span class="hljs-comment">// 9007199254740992000</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x793A;&#x4F8B;&#x8868;&#x660E;&#xFF0C;&#x5927;&#x4E8E;2&#x7684;53&#x6B21;&#x65B9;&#x4EE5;&#x540E;&#xFF0C;&#x591A;&#x51FA;&#x6765;&#x7684;&#x6709;&#x6548;&#x6570;&#x5B57;&#xFF08;&#x6700;&#x540E;&#x4E09;&#x4F4D;&#x7684;<code>111</code>&#xFF09;&#x90FD;&#x4F1A;&#x65E0;&#x6CD5;&#x4FDD;&#x5B58;&#xFF0C;&#x53D8;&#x6210;0&#x3002;</p>
<h3 id="&#x6570;&#x503C;&#x8303;&#x56F4;">&#x6570;&#x503C;&#x8303;&#x56F4;</h3>
<p>&#x6839;&#x636E;&#x6807;&#x51C6;&#xFF0C;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x7684;&#x6307;&#x6570;&#x90E8;&#x5206;&#x7684;&#x957F;&#x5EA6;&#x662F;11&#x4E2A;&#x4E8C;&#x8FDB;&#x5236;&#x4F4D;&#xFF0C;&#x610F;&#x5473;&#x7740;&#x6307;&#x6570;&#x90E8;&#x5206;&#x7684;&#x6700;&#x5927;&#x503C;&#x662F;2047&#xFF08;2&#x7684;11&#x6B21;&#x65B9;&#x51CF;1&#xFF09;&#x3002;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x7684;&#x6307;&#x6570;&#x90E8;&#x5206;&#x7684;&#x503C;&#x6700;&#x5927;&#x4E3A;2047&#xFF0C;&#x5206;&#x51FA;&#x4E00;&#x534A;&#x8868;&#x793A;&#x8D1F;&#x6570;&#xFF0C;&#x5219; JavaScript &#x80FD;&#x591F;&#x8868;&#x793A;&#x7684;&#x6570;&#x503C;&#x8303;&#x56F4;&#x4E3A;2<sup>1024</sup>&#x5230;2<sup>-1023</sup>&#xFF08;&#x5F00;&#x533A;&#x95F4;&#xFF09;&#xFF0C;&#x8D85;&#x51FA;&#x8FD9;&#x4E2A;&#x8303;&#x56F4;&#x7684;&#x6570;&#x65E0;&#x6CD5;&#x8868;&#x793A;&#x3002;</p>
<p>&#x5982;&#x679C;&#x4E00;&#x4E2A;&#x6570;&#x5927;&#x4E8E;&#x7B49;&#x4E8E;2&#x7684;1024&#x6B21;&#x65B9;&#xFF0C;&#x90A3;&#x4E48;&#x5C31;&#x4F1A;&#x53D1;&#x751F;&#x201C;&#x6B63;&#x5411;&#x6EA2;&#x51FA;&#x201D;&#xFF0C;&#x5373; JavaScript &#x65E0;&#x6CD5;&#x8868;&#x793A;&#x8FD9;&#x4E48;&#x5927;&#x7684;&#x6570;&#xFF0C;&#x8FD9;&#x65F6;&#x5C31;&#x4F1A;&#x8FD4;&#x56DE;<code>Infinity</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">1024</span>) <span class="hljs-comment">// Infinity</span>
</code></pre>
<p>&#x5982;&#x679C;&#x4E00;&#x4E2A;&#x6570;&#x5C0F;&#x4E8E;&#x7B49;&#x4E8E;2&#x7684;-1075&#x6B21;&#x65B9;&#xFF08;&#x6307;&#x6570;&#x90E8;&#x5206;&#x6700;&#x5C0F;&#x503C;-1023&#xFF0C;&#x518D;&#x52A0;&#x4E0A;&#x5C0F;&#x6570;&#x90E8;&#x5206;&#x7684;52&#x4F4D;&#xFF09;&#xFF0C;&#x90A3;&#x4E48;&#x5C31;&#x4F1A;&#x53D1;&#x751F;&#x4E3A;&#x201C;&#x8D1F;&#x5411;&#x6EA2;&#x51FA;&#x201D;&#xFF0C;&#x5373; JavaScript &#x65E0;&#x6CD5;&#x8868;&#x793A;&#x8FD9;&#x4E48;&#x5C0F;&#x7684;&#x6570;&#xFF0C;&#x8FD9;&#x65F6;&#x4F1A;&#x76F4;&#x63A5;&#x8FD4;&#x56DE;0&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">-1075</span>) <span class="hljs-comment">// 0</span>
</code></pre>
<p>&#x4E0B;&#x9762;&#x662F;&#x4E00;&#x4E2A;&#x5B9E;&#x9645;&#x7684;&#x4F8B;&#x5B50;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> x = <span class="hljs-number">0.5</span>;

<span class="hljs-keyword">for</span>(<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i &lt; <span class="hljs-number">25</span>; i++) {
  x = x * x;
}

x <span class="hljs-comment">// 0</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5BF9;<code>0.5</code>&#x8FDE;&#x7EED;&#x505A;25&#x6B21;&#x5E73;&#x65B9;&#xFF0C;&#x7531;&#x4E8E;&#x6700;&#x540E;&#x7ED3;&#x679C;&#x592A;&#x63A5;&#x8FD1;0&#xFF0C;&#x8D85;&#x51FA;&#x4E86;&#x53EF;&#x8868;&#x793A;&#x7684;&#x8303;&#x56F4;&#xFF0C;JavaScript &#x5C31;&#x76F4;&#x63A5;&#x5C06;&#x5176;&#x8F6C;&#x4E3A;0&#x3002;</p>
<p>JavaScript &#x63D0;&#x4F9B;<code>Number</code>&#x5BF9;&#x8C61;&#x7684;<code>MAX_VALUE</code>&#x548C;<code>MIN_VALUE</code>&#x5C5E;&#x6027;&#xFF0C;&#x8FD4;&#x56DE;&#x53EF;&#x4EE5;&#x8868;&#x793A;&#x7684;&#x5177;&#x4F53;&#x7684;&#x6700;&#x5927;&#x503C;&#x548C;&#x6700;&#x5C0F;&#x503C;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Number</span>.MAX_VALUE <span class="hljs-comment">// 1.7976931348623157e+308</span>
<span class="hljs-built_in">Number</span>.MIN_VALUE <span class="hljs-comment">// 5e-324</span>
</code></pre>
<h2 id="&#x6570;&#x503C;&#x7684;&#x8868;&#x793A;&#x6CD5;">&#x6570;&#x503C;&#x7684;&#x8868;&#x793A;&#x6CD5;</h2>
<p>JavaScript &#x7684;&#x6570;&#x503C;&#x6709;&#x591A;&#x79CD;&#x8868;&#x793A;&#x65B9;&#x6CD5;&#xFF0C;&#x53EF;&#x4EE5;&#x7528;&#x5B57;&#x9762;&#x5F62;&#x5F0F;&#x76F4;&#x63A5;&#x8868;&#x793A;&#xFF0C;&#x6BD4;&#x5982;<code>35</code>&#xFF08;&#x5341;&#x8FDB;&#x5236;&#xFF09;&#x548C;<code>0xFF</code>&#xFF08;&#x5341;&#x516D;&#x8FDB;&#x5236;&#xFF09;&#x3002;</p>
<p>&#x6570;&#x503C;&#x4E5F;&#x53EF;&#x4EE5;&#x91C7;&#x7528;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#x8868;&#x793A;&#xFF0C;&#x4E0B;&#x9762;&#x662F;&#x51E0;&#x4E2A;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#x7684;&#x4F8B;&#x5B50;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">123e3</span> <span class="hljs-comment">// 123000</span>
<span class="hljs-number">123e-3</span> <span class="hljs-comment">// 0.123</span>
<span class="hljs-number">-3.1E+12</span>
<span class="hljs-number">.1e-23</span>
</code></pre>
<p>&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#x5141;&#x8BB8;&#x5B57;&#x6BCD;<code>e</code>&#x6216;<code>E</code>&#x7684;&#x540E;&#x9762;&#xFF0C;&#x8DDF;&#x7740;&#x4E00;&#x4E2A;&#x6574;&#x6570;&#xFF0C;&#x8868;&#x793A;&#x8FD9;&#x4E2A;&#x6570;&#x503C;&#x7684;&#x6307;&#x6570;&#x90E8;&#x5206;&#x3002;</p>
<p>&#x4EE5;&#x4E0B;&#x4E24;&#x79CD;&#x60C5;&#x51B5;&#xFF0C;JavaScript &#x4F1A;&#x81EA;&#x52A8;&#x5C06;&#x6570;&#x503C;&#x8F6C;&#x4E3A;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#x8868;&#x793A;&#xFF0C;&#x5176;&#x4ED6;&#x60C5;&#x51B5;&#x90FD;&#x91C7;&#x7528;&#x5B57;&#x9762;&#x5F62;&#x5F0F;&#x76F4;&#x63A5;&#x8868;&#x793A;&#x3002;</p>
<p><strong>&#xFF08;1&#xFF09;&#x5C0F;&#x6570;&#x70B9;&#x524D;&#x7684;&#x6570;&#x5B57;&#x591A;&#x4E8E;21&#x4F4D;&#x3002;</strong></p>
<pre><code class="lang-javascript"><span class="hljs-number">1234567890123456789012</span>
<span class="hljs-comment">// 1.2345678901234568e+21</span>

<span class="hljs-number">123456789012345678901</span>
<span class="hljs-comment">// 123456789012345680000</span>
</code></pre>
<p><strong>&#xFF08;2&#xFF09;&#x5C0F;&#x6570;&#x70B9;&#x540E;&#x7684;&#x96F6;&#x591A;&#x4E8E;5&#x4E2A;&#x3002;</strong></p>
<pre><code class="lang-javascript"><span class="hljs-comment">// &#x5C0F;&#x6570;&#x70B9;&#x540E;&#x7D27;&#x8DDF;5&#x4E2A;&#x4EE5;&#x4E0A;&#x7684;&#x96F6;&#xFF0C;</span>
<span class="hljs-comment">// &#x5C31;&#x81EA;&#x52A8;&#x8F6C;&#x4E3A;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;</span>
<span class="hljs-number">0.0000003</span> <span class="hljs-comment">// 3e-7</span>

<span class="hljs-comment">// &#x5426;&#x5219;&#xFF0C;&#x5C31;&#x4FDD;&#x6301;&#x539F;&#x6765;&#x7684;&#x5B57;&#x9762;&#x5F62;&#x5F0F;</span>
<span class="hljs-number">0.000003</span> <span class="hljs-comment">// 0.000003</span>
</code></pre>
<h2 id="&#x6570;&#x503C;&#x7684;&#x8FDB;&#x5236;">&#x6570;&#x503C;&#x7684;&#x8FDB;&#x5236;</h2>
<p>&#x4F7F;&#x7528;&#x5B57;&#x9762;&#x91CF;&#xFF08;literal&#xFF09;&#x76F4;&#x63A5;&#x8868;&#x793A;&#x4E00;&#x4E2A;&#x6570;&#x503C;&#x65F6;&#xFF0C;JavaScript &#x5BF9;&#x6574;&#x6570;&#x63D0;&#x4F9B;&#x56DB;&#x79CD;&#x8FDB;&#x5236;&#x7684;&#x8868;&#x793A;&#x65B9;&#x6CD5;&#xFF1A;&#x5341;&#x8FDB;&#x5236;&#x3001;&#x5341;&#x516D;&#x8FDB;&#x5236;&#x3001;&#x516B;&#x8FDB;&#x5236;&#x3001;&#x4E8C;&#x8FDB;&#x5236;&#x3002;</p>
<ul>
<li>&#x5341;&#x8FDB;&#x5236;&#xFF1A;&#x6CA1;&#x6709;&#x524D;&#x5BFC;0&#x7684;&#x6570;&#x503C;&#x3002;</li>
<li>&#x516B;&#x8FDB;&#x5236;&#xFF1A;&#x6709;&#x524D;&#x7F00;<code>0o</code>&#x6216;<code>0O</code>&#x7684;&#x6570;&#x503C;&#xFF0C;&#x6216;&#x8005;&#x6709;&#x524D;&#x5BFC;0&#x3001;&#x4E14;&#x53EA;&#x7528;&#x5230;0-7&#x7684;&#x516B;&#x4E2A;&#x963F;&#x62C9;&#x4F2F;&#x6570;&#x5B57;&#x7684;&#x6570;&#x503C;&#x3002;</li>
<li>&#x5341;&#x516D;&#x8FDB;&#x5236;&#xFF1A;&#x6709;&#x524D;&#x7F00;<code>0x</code>&#x6216;<code>0X</code>&#x7684;&#x6570;&#x503C;&#x3002;</li>
<li>&#x4E8C;&#x8FDB;&#x5236;&#xFF1A;&#x6709;&#x524D;&#x7F00;<code>0b</code>&#x6216;<code>0B</code>&#x7684;&#x6570;&#x503C;&#x3002;</li>
</ul>
<p>&#x9ED8;&#x8BA4;&#x60C5;&#x51B5;&#x4E0B;&#xFF0C;JavaScript &#x5185;&#x90E8;&#x4F1A;&#x81EA;&#x52A8;&#x5C06;&#x516B;&#x8FDB;&#x5236;&#x3001;&#x5341;&#x516D;&#x8FDB;&#x5236;&#x3001;&#x4E8C;&#x8FDB;&#x5236;&#x8F6C;&#x4E3A;&#x5341;&#x8FDB;&#x5236;&#x3002;&#x4E0B;&#x9762;&#x662F;&#x4E00;&#x4E9B;&#x4F8B;&#x5B50;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">0xff</span> <span class="hljs-comment">// 255</span>
<span class="hljs-number">0o377</span> <span class="hljs-comment">// 255</span>
<span class="hljs-number">0b11</span> <span class="hljs-comment">// 3</span>
</code></pre>
<p>&#x5982;&#x679C;&#x516B;&#x8FDB;&#x5236;&#x3001;&#x5341;&#x516D;&#x8FDB;&#x5236;&#x3001;&#x4E8C;&#x8FDB;&#x5236;&#x7684;&#x6570;&#x503C;&#x91CC;&#x9762;&#xFF0C;&#x51FA;&#x73B0;&#x4E0D;&#x5C5E;&#x4E8E;&#x8BE5;&#x8FDB;&#x5236;&#x7684;&#x6570;&#x5B57;&#xFF0C;&#x5C31;&#x4F1A;&#x62A5;&#x9519;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">0</span>xzz <span class="hljs-comment">// &#x62A5;&#x9519;</span>
<span class="hljs-number">0</span>o88 <span class="hljs-comment">// &#x62A5;&#x9519;</span>
<span class="hljs-number">0</span>b22 <span class="hljs-comment">// &#x62A5;&#x9519;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5341;&#x516D;&#x8FDB;&#x5236;&#x51FA;&#x73B0;&#x4E86;&#x5B57;&#x6BCD;<code>z</code>&#x3001;&#x516B;&#x8FDB;&#x5236;&#x51FA;&#x73B0;&#x6570;&#x5B57;<code>8</code>&#x3001;&#x4E8C;&#x8FDB;&#x5236;&#x51FA;&#x73B0;&#x6570;&#x5B57;<code>2</code>&#xFF0C;&#x56E0;&#x6B64;&#x62A5;&#x9519;&#x3002;</p>
<p>&#x901A;&#x5E38;&#x6765;&#x8BF4;&#xFF0C;&#x6709;&#x524D;&#x5BFC;0&#x7684;&#x6570;&#x503C;&#x4F1A;&#x88AB;&#x89C6;&#x4E3A;&#x516B;&#x8FDB;&#x5236;&#xFF0C;&#x4F46;&#x662F;&#x5982;&#x679C;&#x524D;&#x5BFC;0&#x540E;&#x9762;&#x6709;&#x6570;&#x5B57;<code>8</code>&#x548C;<code>9</code>&#xFF0C;&#x5219;&#x8BE5;&#x6570;&#x503C;&#x88AB;&#x89C6;&#x4E3A;&#x5341;&#x8FDB;&#x5236;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">0888</span> <span class="hljs-comment">// 888</span>
<span class="hljs-number">0777</span> <span class="hljs-comment">// 511</span>
</code></pre>
<p>&#x524D;&#x5BFC;0&#x8868;&#x793A;&#x516B;&#x8FDB;&#x5236;&#xFF0C;&#x5904;&#x7406;&#x65F6;&#x5F88;&#x5BB9;&#x6613;&#x9020;&#x6210;&#x6DF7;&#x4E71;&#x3002;ES5 &#x7684;&#x4E25;&#x683C;&#x6A21;&#x5F0F;&#x548C; ES6&#xFF0C;&#x5DF2;&#x7ECF;&#x5E9F;&#x9664;&#x4E86;&#x8FD9;&#x79CD;&#x8868;&#x793A;&#x6CD5;&#xFF0C;&#x4F46;&#x662F;&#x6D4F;&#x89C8;&#x5668;&#x4E3A;&#x4E86;&#x517C;&#x5BB9;&#x4EE5;&#x524D;&#x7684;&#x4EE3;&#x7801;&#xFF0C;&#x76EE;&#x524D;&#x8FD8;&#x7EE7;&#x7EED;&#x652F;&#x6301;&#x8FD9;&#x79CD;&#x8868;&#x793A;&#x6CD5;&#x3002;</p>
<h2 id="&#x7279;&#x6B8A;&#x6570;&#x503C;">&#x7279;&#x6B8A;&#x6570;&#x503C;</h2>
<p>JavaScript &#x63D0;&#x4F9B;&#x4E86;&#x51E0;&#x4E2A;&#x7279;&#x6B8A;&#x7684;&#x6570;&#x503C;&#x3002;</p>
<h3 id="&#x6B63;&#x96F6;&#x548C;&#x8D1F;&#x96F6;">&#x6B63;&#x96F6;&#x548C;&#x8D1F;&#x96F6;</h3>
<p>&#x524D;&#x9762;&#x8BF4;&#x8FC7;&#xFF0C;JavaScript &#x7684;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x4E4B;&#x4E2D;&#xFF0C;&#x6709;&#x4E00;&#x4E2A;&#x4E8C;&#x8FDB;&#x5236;&#x4F4D;&#x662F;&#x7B26;&#x53F7;&#x4F4D;&#x3002;&#x8FD9;&#x610F;&#x5473;&#x7740;&#xFF0C;&#x4EFB;&#x4F55;&#x4E00;&#x4E2A;&#x6570;&#x90FD;&#x6709;&#x4E00;&#x4E2A;&#x5BF9;&#x5E94;&#x7684;&#x8D1F;&#x503C;&#xFF0C;&#x5C31;&#x8FDE;<code>0</code>&#x4E5F;&#x4E0D;&#x4F8B;&#x5916;&#x3002;</p>
<p>JavaScript &#x5185;&#x90E8;&#x5B9E;&#x9645;&#x4E0A;&#x5B58;&#x5728;2&#x4E2A;<code>0</code>&#xFF1A;&#x4E00;&#x4E2A;&#x662F;<code>+0</code>&#xFF0C;&#x4E00;&#x4E2A;&#x662F;<code>-0</code>&#xFF0C;&#x533A;&#x522B;&#x5C31;&#x662F;64&#x4F4D;&#x6D6E;&#x70B9;&#x6570;&#x8868;&#x793A;&#x6CD5;&#x7684;&#x7B26;&#x53F7;&#x4F4D;&#x4E0D;&#x540C;&#x3002;&#x5B83;&#x4EEC;&#x662F;&#x7B49;&#x4EF7;&#x7684;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">-0</span> === +<span class="hljs-number">0</span> <span class="hljs-comment">// true</span>
<span class="hljs-number">0</span> === <span class="hljs-number">-0</span> <span class="hljs-comment">// true</span>
<span class="hljs-number">0</span> === +<span class="hljs-number">0</span> <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x51E0;&#x4E4E;&#x6240;&#x6709;&#x573A;&#x5408;&#xFF0C;&#x6B63;&#x96F6;&#x548C;&#x8D1F;&#x96F6;&#x90FD;&#x4F1A;&#x88AB;&#x5F53;&#x4F5C;&#x6B63;&#x5E38;&#x7684;<code>0</code>&#x3002;</p>
<pre><code class="lang-javascript">+<span class="hljs-number">0</span> <span class="hljs-comment">// 0</span>
<span class="hljs-number">-0</span> <span class="hljs-comment">// 0</span>
(<span class="hljs-number">-0</span>).toString() <span class="hljs-comment">// &apos;0&apos;</span>
(+<span class="hljs-number">0</span>).toString() <span class="hljs-comment">// &apos;0&apos;</span>
</code></pre>
<p>&#x552F;&#x4E00;&#x6709;&#x533A;&#x522B;&#x7684;&#x573A;&#x5408;&#x662F;&#xFF0C;<code>+0</code>&#x6216;<code>-0</code>&#x5F53;&#x4F5C;&#x5206;&#x6BCD;&#xFF0C;&#x8FD4;&#x56DE;&#x7684;&#x503C;&#x662F;&#x4E0D;&#x76F8;&#x7B49;&#x7684;&#x3002;</p>
<pre><code class="lang-javascript">(<span class="hljs-number">1</span> / +<span class="hljs-number">0</span>) === (<span class="hljs-number">1</span> / <span class="hljs-number">-0</span>) <span class="hljs-comment">// false</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x4E4B;&#x6240;&#x4EE5;&#x51FA;&#x73B0;&#x8FD9;&#x6837;&#x7ED3;&#x679C;&#xFF0C;&#x662F;&#x56E0;&#x4E3A;&#x9664;&#x4EE5;&#x6B63;&#x96F6;&#x5F97;&#x5230;<code>+Infinity</code>&#xFF0C;&#x9664;&#x4EE5;&#x8D1F;&#x96F6;&#x5F97;&#x5230;<code>-Infinity</code>&#xFF0C;&#x8FD9;&#x4E24;&#x8005;&#x662F;&#x4E0D;&#x76F8;&#x7B49;&#x7684;&#xFF08;&#x5173;&#x4E8E;<code>Infinity</code>&#x8BE6;&#x89C1;&#x4E0B;&#x6587;&#xFF09;&#x3002;</p>
<h3 id="nan">NaN</h3>
<p><strong>&#xFF08;1&#xFF09;&#x542B;&#x4E49;</strong></p>
<p><code>NaN</code>&#x662F; JavaScript &#x7684;&#x7279;&#x6B8A;&#x503C;&#xFF0C;&#x8868;&#x793A;&#x201C;&#x975E;&#x6570;&#x5B57;&#x201D;&#xFF08;Not a Number&#xFF09;&#xFF0C;&#x4E3B;&#x8981;&#x51FA;&#x73B0;&#x5728;&#x5C06;&#x5B57;&#x7B26;&#x4E32;&#x89E3;&#x6790;&#x6210;&#x6570;&#x5B57;&#x51FA;&#x9519;&#x7684;&#x573A;&#x5408;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">5</span> - <span class="hljs-string">&apos;x&apos;</span> <span class="hljs-comment">// NaN</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x8FD0;&#x884C;&#x65F6;&#xFF0C;&#x4F1A;&#x81EA;&#x52A8;&#x5C06;&#x5B57;&#x7B26;&#x4E32;<code>x</code>&#x8F6C;&#x4E3A;&#x6570;&#x503C;&#xFF0C;&#x4F46;&#x662F;&#x7531;&#x4E8E;<code>x</code>&#x4E0D;&#x662F;&#x6570;&#x503C;&#xFF0C;&#x6240;&#x4EE5;&#x6700;&#x540E;&#x5F97;&#x5230;&#x7ED3;&#x679C;&#x4E3A;<code>NaN</code>&#xFF0C;&#x8868;&#x793A;&#x5B83;&#x662F;&#x201C;&#x975E;&#x6570;&#x5B57;&#x201D;&#xFF08;<code>NaN</code>&#xFF09;&#x3002;</p>
<p>&#x53E6;&#x5916;&#xFF0C;&#x4E00;&#x4E9B;&#x6570;&#x5B66;&#x51FD;&#x6570;&#x7684;&#x8FD0;&#x7B97;&#x7ED3;&#x679C;&#x4F1A;&#x51FA;&#x73B0;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Math</span>.acos(<span class="hljs-number">2</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">Math</span>.log(<span class="hljs-number">-1</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">Math</span>.sqrt(<span class="hljs-number">-1</span>) <span class="hljs-comment">// NaN</span>
</code></pre>
<p><code>0</code>&#x9664;&#x4EE5;<code>0</code>&#x4E5F;&#x4F1A;&#x5F97;&#x5230;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">0</span> / <span class="hljs-number">0</span> <span class="hljs-comment">// NaN</span>
</code></pre>
<p>&#x9700;&#x8981;&#x6CE8;&#x610F;&#x7684;&#x662F;&#xFF0C;<code>NaN</code>&#x4E0D;&#x662F;&#x72EC;&#x7ACB;&#x7684;&#x6570;&#x636E;&#x7C7B;&#x578B;&#xFF0C;&#x800C;&#x662F;&#x4E00;&#x4E2A;&#x7279;&#x6B8A;&#x6570;&#x503C;&#xFF0C;&#x5B83;&#x7684;&#x6570;&#x636E;&#x7C7B;&#x578B;&#x4F9D;&#x7136;&#x5C5E;&#x4E8E;<code>Number</code>&#xFF0C;&#x4F7F;&#x7528;<code>typeof</code>&#x8FD0;&#x7B97;&#x7B26;&#x53EF;&#x4EE5;&#x770B;&#x5F97;&#x5F88;&#x6E05;&#x695A;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">typeof</span> <span class="hljs-literal">NaN</span> <span class="hljs-comment">// &apos;number&apos;</span>
</code></pre>
<p><strong>&#xFF08;2&#xFF09;&#x8FD0;&#x7B97;&#x89C4;&#x5219;</strong></p>
<p><code>NaN</code>&#x4E0D;&#x7B49;&#x4E8E;&#x4EFB;&#x4F55;&#x503C;&#xFF0C;&#x5305;&#x62EC;&#x5B83;&#x672C;&#x8EAB;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">NaN</span> === <span class="hljs-literal">NaN</span> <span class="hljs-comment">// false</span>
</code></pre>
<p>&#x6570;&#x7EC4;&#x7684;<code>indexOf</code>&#x65B9;&#x6CD5;&#x5185;&#x90E8;&#x4F7F;&#x7528;&#x7684;&#x662F;&#x4E25;&#x683C;&#x76F8;&#x7B49;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x6240;&#x4EE5;&#x8BE5;&#x65B9;&#x6CD5;&#x5BF9;<code>NaN</code>&#x4E0D;&#x6210;&#x7ACB;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-literal">NaN</span>].indexOf(<span class="hljs-literal">NaN</span>) <span class="hljs-comment">// -1</span>
</code></pre>
<p><code>NaN</code>&#x5728;&#x5E03;&#x5C14;&#x8FD0;&#x7B97;&#x65F6;&#x88AB;&#x5F53;&#x4F5C;<code>false</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Boolean</span>(<span class="hljs-literal">NaN</span>) <span class="hljs-comment">// false</span>
</code></pre>
<p><code>NaN</code>&#x4E0E;&#x4EFB;&#x4F55;&#x6570;&#xFF08;&#x5305;&#x62EC;&#x5B83;&#x81EA;&#x5DF1;&#xFF09;&#x7684;&#x8FD0;&#x7B97;&#xFF0C;&#x5F97;&#x5230;&#x7684;&#x90FD;&#x662F;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">NaN</span> + <span class="hljs-number">32</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">NaN</span> - <span class="hljs-number">32</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">NaN</span> * <span class="hljs-number">32</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">NaN</span> / <span class="hljs-number">32</span> <span class="hljs-comment">// NaN</span>
</code></pre>
<h3 id="infinity">Infinity</h3>
<p><strong>&#xFF08;1&#xFF09;&#x542B;&#x4E49;</strong></p>
<p><code>Infinity</code>&#x8868;&#x793A;&#x201C;&#x65E0;&#x7A77;&#x201D;&#xFF0C;&#x7528;&#x6765;&#x8868;&#x793A;&#x4E24;&#x79CD;&#x573A;&#x666F;&#x3002;&#x4E00;&#x79CD;&#x662F;&#x4E00;&#x4E2A;&#x6B63;&#x7684;&#x6570;&#x503C;&#x592A;&#x5927;&#xFF0C;&#x6216;&#x4E00;&#x4E2A;&#x8D1F;&#x7684;&#x6570;&#x503C;&#x592A;&#x5C0F;&#xFF0C;&#x65E0;&#x6CD5;&#x8868;&#x793A;&#xFF1B;&#x53E6;&#x4E00;&#x79CD;&#x662F;&#x975E;0&#x6570;&#x503C;&#x9664;&#x4EE5;0&#xFF0C;&#x5F97;&#x5230;<code>Infinity</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-comment">// &#x573A;&#x666F;&#x4E00;</span>
<span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">1024</span>)
<span class="hljs-comment">// Infinity</span>

<span class="hljs-comment">// &#x573A;&#x666F;&#x4E8C;</span>
<span class="hljs-number">0</span> / <span class="hljs-number">0</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-number">1</span> / <span class="hljs-number">0</span> <span class="hljs-comment">// Infinity</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x7B2C;&#x4E00;&#x4E2A;&#x573A;&#x666F;&#x662F;&#x4E00;&#x4E2A;&#x8868;&#x8FBE;&#x5F0F;&#x7684;&#x8BA1;&#x7B97;&#x7ED3;&#x679C;&#x592A;&#x5927;&#xFF0C;&#x8D85;&#x51FA;&#x4E86;&#x80FD;&#x591F;&#x8868;&#x793A;&#x7684;&#x8303;&#x56F4;&#xFF0C;&#x56E0;&#x6B64;&#x8FD4;&#x56DE;<code>Infinity</code>&#x3002;&#x7B2C;&#x4E8C;&#x4E2A;&#x573A;&#x666F;&#x662F;<code>0</code>&#x9664;&#x4EE5;<code>0</code>&#x4F1A;&#x5F97;&#x5230;<code>NaN</code>&#xFF0C;&#x800C;&#x975E;0&#x6570;&#x503C;&#x9664;&#x4EE5;<code>0</code>&#xFF0C;&#x4F1A;&#x8FD4;&#x56DE;<code>Infinity</code>&#x3002;</p>
<p><code>Infinity</code>&#x6709;&#x6B63;&#x8D1F;&#x4E4B;&#x5206;&#xFF0C;<code>Infinity</code>&#x8868;&#x793A;&#x6B63;&#x7684;&#x65E0;&#x7A77;&#xFF0C;<code>-Infinity</code>&#x8868;&#x793A;&#x8D1F;&#x7684;&#x65E0;&#x7A77;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">Infinity</span> === -<span class="hljs-literal">Infinity</span> <span class="hljs-comment">// false</span>

<span class="hljs-number">1</span> / <span class="hljs-number">-0</span> <span class="hljs-comment">// -Infinity</span>
<span class="hljs-number">-1</span> / <span class="hljs-number">-0</span> <span class="hljs-comment">// Infinity</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x975E;&#x96F6;&#x6B63;&#x6570;&#x9664;&#x4EE5;<code>-0</code>&#xFF0C;&#x4F1A;&#x5F97;&#x5230;<code>-Infinity</code>&#xFF0C;&#x8D1F;&#x6570;&#x9664;&#x4EE5;<code>-0</code>&#xFF0C;&#x4F1A;&#x5F97;&#x5230;<code>Infinity</code>&#x3002;</p>
<p>&#x7531;&#x4E8E;&#x6570;&#x503C;&#x6B63;&#x5411;&#x6EA2;&#x51FA;&#xFF08;overflow&#xFF09;&#x3001;&#x8D1F;&#x5411;&#x6EA2;&#x51FA;&#xFF08;underflow&#xFF09;&#x548C;&#x88AB;<code>0</code>&#x9664;&#xFF0C;JavaScript &#x90FD;&#x4E0D;&#x62A5;&#x9519;&#xFF0C;&#x6240;&#x4EE5;&#x5355;&#x7EAF;&#x7684;&#x6570;&#x5B66;&#x8FD0;&#x7B97;&#x51E0;&#x4E4E;&#x6CA1;&#x6709;&#x53EF;&#x80FD;&#x629B;&#x51FA;&#x9519;&#x8BEF;&#x3002;</p>
<p><code>Infinity</code>&#x5927;&#x4E8E;&#x4E00;&#x5207;&#x6570;&#x503C;&#xFF08;&#x9664;&#x4E86;<code>NaN</code>&#xFF09;&#xFF0C;<code>-Infinity</code>&#x5C0F;&#x4E8E;&#x4E00;&#x5207;&#x6570;&#x503C;&#xFF08;&#x9664;&#x4E86;<code>NaN</code>&#xFF09;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">Infinity</span> &gt; <span class="hljs-number">1000</span> <span class="hljs-comment">// true</span>
-<span class="hljs-literal">Infinity</span> &lt; <span class="hljs-number">-1000</span> <span class="hljs-comment">// true</span>
</code></pre>
<p><code>Infinity</code>&#x4E0E;<code>NaN</code>&#x6BD4;&#x8F83;&#xFF0C;&#x603B;&#x662F;&#x8FD4;&#x56DE;<code>false</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">Infinity</span> &gt; <span class="hljs-literal">NaN</span> <span class="hljs-comment">// false</span>
-<span class="hljs-literal">Infinity</span> &gt; <span class="hljs-literal">NaN</span> <span class="hljs-comment">// false</span>

<span class="hljs-literal">Infinity</span> &lt; <span class="hljs-literal">NaN</span> <span class="hljs-comment">// false</span>
-<span class="hljs-literal">Infinity</span> &lt; <span class="hljs-literal">NaN</span> <span class="hljs-comment">// false</span>
</code></pre>
<p><strong>&#xFF08;2&#xFF09;&#x8FD0;&#x7B97;&#x89C4;&#x5219;</strong></p>
<p><code>Infinity</code>&#x7684;&#x56DB;&#x5219;&#x8FD0;&#x7B97;&#xFF0C;&#x7B26;&#x5408;&#x65E0;&#x7A77;&#x7684;&#x6570;&#x5B66;&#x8BA1;&#x7B97;&#x89C4;&#x5219;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">5</span> * <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// Infinity</span>
<span class="hljs-number">5</span> - <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// -Infinity</span>
<span class="hljs-literal">Infinity</span> / <span class="hljs-number">5</span> <span class="hljs-comment">// Infinity</span>
<span class="hljs-number">5</span> / <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// 0</span>
</code></pre>
<p>0&#x4E58;&#x4EE5;<code>Infinity</code>&#xFF0C;&#x8FD4;&#x56DE;<code>NaN</code>&#xFF1B;0&#x9664;&#x4EE5;<code>Infinity</code>&#xFF0C;&#x8FD4;&#x56DE;<code>0</code>&#xFF1B;<code>Infinity</code>&#x9664;&#x4EE5;0&#xFF0C;&#x8FD4;&#x56DE;<code>Infinity</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-number">0</span> * <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-number">0</span> / <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// 0</span>
<span class="hljs-literal">Infinity</span> / <span class="hljs-number">0</span> <span class="hljs-comment">// Infinity</span>
</code></pre>
<p><code>Infinity</code>&#x52A0;&#x4E0A;&#x6216;&#x4E58;&#x4EE5;<code>Infinity</code>&#xFF0C;&#x8FD4;&#x56DE;&#x7684;&#x8FD8;&#x662F;<code>Infinity</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">Infinity</span> + <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// Infinity</span>
<span class="hljs-literal">Infinity</span> * <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// Infinity</span>
</code></pre>
<p><code>Infinity</code>&#x51CF;&#x53BB;&#x6216;&#x9664;&#x4EE5;<code>Infinity</code>&#xFF0C;&#x5F97;&#x5230;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">Infinity</span> - <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">Infinity</span> / <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
</code></pre>
<p><code>Infinity</code>&#x4E0E;<code>null</code>&#x8BA1;&#x7B97;&#x65F6;&#xFF0C;<code>null</code>&#x4F1A;&#x8F6C;&#x6210;0&#xFF0C;&#x7B49;&#x540C;&#x4E8E;&#x4E0E;<code>0</code>&#x7684;&#x8BA1;&#x7B97;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">null</span> * <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">null</span> / <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// 0</span>
<span class="hljs-literal">Infinity</span> / <span class="hljs-literal">null</span> <span class="hljs-comment">// Infinity</span>
</code></pre>
<p><code>Infinity</code>&#x4E0E;<code>undefined</code>&#x8BA1;&#x7B97;&#xFF0C;&#x8FD4;&#x56DE;&#x7684;&#x90FD;&#x662F;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-literal">undefined</span> + <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">undefined</span> - <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">undefined</span> * <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">undefined</span> / <span class="hljs-literal">Infinity</span> <span class="hljs-comment">// NaN</span>
<span class="hljs-literal">Infinity</span> / <span class="hljs-literal">undefined</span> <span class="hljs-comment">// NaN</span>
</code></pre>
<h2 id="&#x4E0E;&#x6570;&#x503C;&#x76F8;&#x5173;&#x7684;&#x5168;&#x5C40;&#x65B9;&#x6CD5;">&#x4E0E;&#x6570;&#x503C;&#x76F8;&#x5173;&#x7684;&#x5168;&#x5C40;&#x65B9;&#x6CD5;</h2>
<h3 id="parseint">parseInt()</h3>
<p><strong>&#xFF08;1&#xFF09;&#x57FA;&#x672C;&#x7528;&#x6CD5;</strong></p>
<p><code>parseInt</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5C06;&#x5B57;&#x7B26;&#x4E32;&#x8F6C;&#x4E3A;&#x6574;&#x6570;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;123&apos;</span>) <span class="hljs-comment">// 123</span>
</code></pre>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x5934;&#x90E8;&#x6709;&#x7A7A;&#x683C;&#xFF0C;&#x7A7A;&#x683C;&#x4F1A;&#x88AB;&#x81EA;&#x52A8;&#x53BB;&#x9664;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;   81&apos;</span>) <span class="hljs-comment">// 81</span>
</code></pre>
<p>&#x5982;&#x679C;<code>parseInt</code>&#x7684;&#x53C2;&#x6570;&#x4E0D;&#x662F;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x5219;&#x4F1A;&#x5148;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;&#x518D;&#x8F6C;&#x6362;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-number">1.23</span>) <span class="hljs-comment">// 1</span>
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1.23&apos;</span>) <span class="hljs-comment">// 1</span>
</code></pre>
<p>&#x5B57;&#x7B26;&#x4E32;&#x8F6C;&#x4E3A;&#x6574;&#x6570;&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x662F;&#x4E00;&#x4E2A;&#x4E2A;&#x5B57;&#x7B26;&#x4F9D;&#x6B21;&#x8F6C;&#x6362;&#xFF0C;&#x5982;&#x679C;&#x9047;&#x5230;&#x4E0D;&#x80FD;&#x8F6C;&#x4E3A;&#x6570;&#x5B57;&#x7684;&#x5B57;&#x7B26;&#xFF0C;&#x5C31;&#x4E0D;&#x518D;&#x8FDB;&#x884C;&#x4E0B;&#x53BB;&#xFF0C;&#x8FD4;&#x56DE;&#x5DF2;&#x7ECF;&#x8F6C;&#x597D;&#x7684;&#x90E8;&#x5206;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;8a&apos;</span>) <span class="hljs-comment">// 8</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;12**&apos;</span>) <span class="hljs-comment">// 12</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;12.34&apos;</span>) <span class="hljs-comment">// 12</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;15e2&apos;</span>) <span class="hljs-comment">// 15</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;15px&apos;</span>) <span class="hljs-comment">// 15</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>parseInt</code>&#x7684;&#x53C2;&#x6570;&#x90FD;&#x662F;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x7ED3;&#x679C;&#x53EA;&#x8FD4;&#x56DE;&#x5B57;&#x7B26;&#x4E32;&#x5934;&#x90E8;&#x53EF;&#x4EE5;&#x8F6C;&#x4E3A;&#x6570;&#x5B57;&#x7684;&#x90E8;&#x5206;&#x3002;</p>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E0D;&#x80FD;&#x8F6C;&#x5316;&#x4E3A;&#x6570;&#x5B57;&#xFF08;&#x540E;&#x9762;&#x8DDF;&#x7740;&#x6570;&#x5B57;&#x7684;&#x6B63;&#x8D1F;&#x53F7;&#x9664;&#x5916;&#xFF09;&#xFF0C;&#x8FD4;&#x56DE;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;abc&apos;</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;.3&apos;</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;&apos;</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;+&apos;</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;+1&apos;</span>) <span class="hljs-comment">// 1</span>
</code></pre>
<p>&#x6240;&#x4EE5;&#xFF0C;<code>parseInt</code>&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x53EA;&#x6709;&#x4E24;&#x79CD;&#x53EF;&#x80FD;&#xFF0C;&#x8981;&#x4E48;&#x662F;&#x4E00;&#x4E2A;&#x5341;&#x8FDB;&#x5236;&#x6574;&#x6570;&#xFF0C;&#x8981;&#x4E48;&#x662F;<code>NaN</code>&#x3002;</p>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x4EE5;<code>0x</code>&#x6216;<code>0X</code>&#x5F00;&#x5934;&#xFF0C;<code>parseInt</code>&#x4F1A;&#x5C06;&#x5176;&#x6309;&#x7167;&#x5341;&#x516D;&#x8FDB;&#x5236;&#x6570;&#x89E3;&#x6790;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;0x10&apos;</span>) <span class="hljs-comment">// 16</span>
</code></pre>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x4EE5;<code>0</code>&#x5F00;&#x5934;&#xFF0C;&#x5C06;&#x5176;&#x6309;&#x7167;10&#x8FDB;&#x5236;&#x89E3;&#x6790;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;011&apos;</span>) <span class="hljs-comment">// 11</span>
</code></pre>
<p>&#x5BF9;&#x4E8E;&#x90A3;&#x4E9B;&#x4F1A;&#x81EA;&#x52A8;&#x8F6C;&#x4E3A;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#x7684;&#x6570;&#x5B57;&#xFF0C;<code>parseInt</code>&#x4F1A;&#x5C06;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#x7684;&#x8868;&#x793A;&#x65B9;&#x6CD5;&#x89C6;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x56E0;&#x6B64;&#x5BFC;&#x81F4;&#x4E00;&#x4E9B;&#x5947;&#x602A;&#x7684;&#x7ED3;&#x679C;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-number">1000000000000000000000.5</span>) <span class="hljs-comment">// 1</span>
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1e+21&apos;</span>) <span class="hljs-comment">// 1</span>

<span class="hljs-built_in">parseInt</span>(<span class="hljs-number">0.0000008</span>) <span class="hljs-comment">// 8</span>
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;8e-7&apos;</span>) <span class="hljs-comment">// 8</span>
</code></pre>
<p><strong>&#xFF08;2&#xFF09;&#x8FDB;&#x5236;&#x8F6C;&#x6362;</strong></p>
<p><code>parseInt</code>&#x65B9;&#x6CD5;&#x8FD8;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF08;2&#x5230;36&#x4E4B;&#x95F4;&#xFF09;&#xFF0C;&#x8868;&#x793A;&#x88AB;&#x89E3;&#x6790;&#x7684;&#x503C;&#x7684;&#x8FDB;&#x5236;&#xFF0C;&#x8FD4;&#x56DE;&#x8BE5;&#x503C;&#x5BF9;&#x5E94;&#x7684;&#x5341;&#x8FDB;&#x5236;&#x6570;&#x3002;&#x9ED8;&#x8BA4;&#x60C5;&#x51B5;&#x4E0B;&#xFF0C;<code>parseInt</code>&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x4E3A;10&#xFF0C;&#x5373;&#x9ED8;&#x8BA4;&#x662F;&#x5341;&#x8FDB;&#x5236;&#x8F6C;&#x5341;&#x8FDB;&#x5236;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1000&apos;</span>) <span class="hljs-comment">// 1000</span>
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1000&apos;</span>, <span class="hljs-number">10</span>) <span class="hljs-comment">// 1000</span>
</code></pre>
<p>&#x4E0B;&#x9762;&#x662F;&#x8F6C;&#x6362;&#x6307;&#x5B9A;&#x8FDB;&#x5236;&#x7684;&#x6570;&#x7684;&#x4F8B;&#x5B50;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1000&apos;</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// 8</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1000&apos;</span>, <span class="hljs-number">6</span>) <span class="hljs-comment">// 216</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1000&apos;</span>, <span class="hljs-number">8</span>) <span class="hljs-comment">// 512</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x4E8C;&#x8FDB;&#x5236;&#x3001;&#x516D;&#x8FDB;&#x5236;&#x3001;&#x516B;&#x8FDB;&#x5236;&#x7684;<code>1000</code>&#xFF0C;&#x5206;&#x522B;&#x7B49;&#x4E8E;&#x5341;&#x8FDB;&#x5236;&#x7684;8&#x3001;216&#x548C;512&#x3002;&#x8FD9;&#x610F;&#x5473;&#x7740;&#xFF0C;&#x53EF;&#x4EE5;&#x7528;<code>parseInt</code>&#x65B9;&#x6CD5;&#x8FDB;&#x884C;&#x8FDB;&#x5236;&#x7684;&#x8F6C;&#x6362;&#x3002;</p>
<p>&#x5982;&#x679C;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x4E0D;&#x662F;&#x6570;&#x503C;&#xFF0C;&#x4F1A;&#x88AB;&#x81EA;&#x52A8;&#x8F6C;&#x4E3A;&#x4E00;&#x4E2A;&#x6574;&#x6570;&#x3002;&#x8FD9;&#x4E2A;&#x6574;&#x6570;&#x53EA;&#x6709;&#x5728;2&#x5230;36&#x4E4B;&#x95F4;&#xFF0C;&#x624D;&#x80FD;&#x5F97;&#x5230;&#x6709;&#x610F;&#x4E49;&#x7684;&#x7ED3;&#x679C;&#xFF0C;&#x8D85;&#x51FA;&#x8FD9;&#x4E2A;&#x8303;&#x56F4;&#xFF0C;&#x5219;&#x8FD4;&#x56DE;<code>NaN</code>&#x3002;&#x5982;&#x679C;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x662F;<code>0</code>&#x3001;<code>undefined</code>&#x548C;<code>null</code>&#xFF0C;&#x5219;&#x76F4;&#x63A5;&#x5FFD;&#x7565;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;10&apos;</span>, <span class="hljs-number">37</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;10&apos;</span>, <span class="hljs-number">1</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;10&apos;</span>, <span class="hljs-number">0</span>) <span class="hljs-comment">// 10</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;10&apos;</span>, <span class="hljs-literal">null</span>) <span class="hljs-comment">// 10</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;10&apos;</span>, <span class="hljs-literal">undefined</span>) <span class="hljs-comment">// 10</span>
</code></pre>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x5305;&#x542B;&#x5BF9;&#x4E8E;&#x6307;&#x5B9A;&#x8FDB;&#x5236;&#x65E0;&#x610F;&#x4E49;&#x7684;&#x5B57;&#x7B26;&#xFF0C;&#x5219;&#x4ECE;&#x6700;&#x9AD8;&#x4F4D;&#x5F00;&#x59CB;&#xFF0C;&#x53EA;&#x8FD4;&#x56DE;&#x53EF;&#x4EE5;&#x8F6C;&#x6362;&#x7684;&#x6570;&#x503C;&#x3002;&#x5982;&#x679C;&#x6700;&#x9AD8;&#x4F4D;&#x65E0;&#x6CD5;&#x8F6C;&#x6362;&#xFF0C;&#x5219;&#x76F4;&#x63A5;&#x8FD4;&#x56DE;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;1546&apos;</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// 1</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;546&apos;</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// NaN</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5BF9;&#x4E8E;&#x4E8C;&#x8FDB;&#x5236;&#x6765;&#x8BF4;&#xFF0C;<code>1</code>&#x662F;&#x6709;&#x610F;&#x4E49;&#x7684;&#x5B57;&#x7B26;&#xFF0C;<code>5</code>&#x3001;<code>4</code>&#x3001;<code>6</code>&#x90FD;&#x662F;&#x65E0;&#x610F;&#x4E49;&#x7684;&#x5B57;&#x7B26;&#xFF0C;&#x6240;&#x4EE5;&#x7B2C;&#x4E00;&#x884C;&#x8FD4;&#x56DE;1&#xFF0C;&#x7B2C;&#x4E8C;&#x884C;&#x8FD4;&#x56DE;<code>NaN</code>&#x3002;</p>
<p>&#x524D;&#x9762;&#x8BF4;&#x8FC7;&#xFF0C;&#x5982;&#x679C;<code>parseInt</code>&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x4E0D;&#x662F;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x4F1A;&#x88AB;&#x5148;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;&#x3002;&#x8FD9;&#x4F1A;&#x5BFC;&#x81F4;&#x4E00;&#x4E9B;&#x4EE4;&#x4EBA;&#x610F;&#x5916;&#x7684;&#x7ED3;&#x679C;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-number">0x11</span>, <span class="hljs-number">36</span>) <span class="hljs-comment">// 43</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-number">0x11</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// 1</span>

<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-built_in">String</span>(<span class="hljs-number">0x11</span>), <span class="hljs-number">36</span>)
<span class="hljs-built_in">parseInt</span>(<span class="hljs-built_in">String</span>(<span class="hljs-number">0x11</span>), <span class="hljs-number">2</span>)

<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;17&apos;</span>, <span class="hljs-number">36</span>)
<span class="hljs-built_in">parseInt</span>(<span class="hljs-string">&apos;17&apos;</span>, <span class="hljs-number">2</span>)
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5341;&#x516D;&#x8FDB;&#x5236;&#x7684;<code>0x11</code>&#x4F1A;&#x88AB;&#x5148;&#x8F6C;&#x4E3A;&#x5341;&#x8FDB;&#x5236;&#x7684;17&#xFF0C;&#x518D;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;&#x3002;&#x7136;&#x540E;&#xFF0C;&#x518D;&#x7528;36&#x8FDB;&#x5236;&#x6216;&#x4E8C;&#x8FDB;&#x5236;&#x89E3;&#x8BFB;&#x5B57;&#x7B26;&#x4E32;<code>17</code>&#xFF0C;&#x6700;&#x540E;&#x8FD4;&#x56DE;&#x7ED3;&#x679C;<code>43</code>&#x548C;<code>1</code>&#x3002;</p>
<p>&#x8FD9;&#x79CD;&#x5904;&#x7406;&#x65B9;&#x5F0F;&#xFF0C;&#x5BF9;&#x4E8E;&#x516B;&#x8FDB;&#x5236;&#x7684;&#x524D;&#x7F00;0&#xFF0C;&#x5C24;&#x5176;&#x9700;&#x8981;&#x6CE8;&#x610F;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseInt</span>(<span class="hljs-number">011</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// NaN</span>

<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-built_in">String</span>(<span class="hljs-number">011</span>), <span class="hljs-number">2</span>)

<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">parseInt</span>(<span class="hljs-built_in">String</span>(<span class="hljs-number">9</span>), <span class="hljs-number">2</span>)
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x7B2C;&#x4E00;&#x884C;&#x7684;<code>011</code>&#x4F1A;&#x88AB;&#x5148;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;<code>9</code>&#xFF0C;&#x56E0;&#x4E3A;<code>9</code>&#x4E0D;&#x662F;&#x4E8C;&#x8FDB;&#x5236;&#x7684;&#x6709;&#x6548;&#x5B57;&#x7B26;&#xFF0C;&#x6240;&#x4EE5;&#x8FD4;&#x56DE;<code>NaN</code>&#x3002;&#x5982;&#x679C;&#x76F4;&#x63A5;&#x8BA1;&#x7B97;<code>parseInt(&apos;011&apos;, 2)</code>&#xFF0C;<code>011</code>&#x5219;&#x662F;&#x4F1A;&#x88AB;&#x5F53;&#x4F5C;&#x4E8C;&#x8FDB;&#x5236;&#x5904;&#x7406;&#xFF0C;&#x8FD4;&#x56DE;3&#x3002;</p>
<p>JavaScript &#x4E0D;&#x518D;&#x5141;&#x8BB8;&#x5C06;&#x5E26;&#x6709;&#x524D;&#x7F00;0&#x7684;&#x6570;&#x5B57;&#x89C6;&#x4E3A;&#x516B;&#x8FDB;&#x5236;&#x6570;&#xFF0C;&#x800C;&#x662F;&#x8981;&#x6C42;&#x5FFD;&#x7565;&#x8FD9;&#x4E2A;<code>0</code>&#x3002;&#x4F46;&#x662F;&#xFF0C;&#x4E3A;&#x4E86;&#x4FDD;&#x8BC1;&#x517C;&#x5BB9;&#x6027;&#xFF0C;&#x5927;&#x90E8;&#x5206;&#x6D4F;&#x89C8;&#x5668;&#x5E76;&#x6CA1;&#x6709;&#x90E8;&#x7F72;&#x8FD9;&#x4E00;&#x6761;&#x89C4;&#x5B9A;&#x3002;</p>
<h3 id="parsefloat">parseFloat()</h3>
<p><code>parseFloat</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5C06;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E32;&#x8F6C;&#x4E3A;&#x6D6E;&#x70B9;&#x6570;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;3.14&apos;</span>) <span class="hljs-comment">// 3.14</span>
</code></pre>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x7B26;&#x5408;&#x79D1;&#x5B66;&#x8BA1;&#x6570;&#x6CD5;&#xFF0C;&#x5219;&#x4F1A;&#x8FDB;&#x884C;&#x76F8;&#x5E94;&#x7684;&#x8F6C;&#x6362;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;314e-2&apos;</span>) <span class="hljs-comment">// 3.14</span>
<span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;0.0314E+2&apos;</span>) <span class="hljs-comment">// 3.14</span>
</code></pre>
<p>&#x5982;&#x679C;&#x5B57;&#x7B26;&#x4E32;&#x5305;&#x542B;&#x4E0D;&#x80FD;&#x8F6C;&#x4E3A;&#x6D6E;&#x70B9;&#x6570;&#x7684;&#x5B57;&#x7B26;&#xFF0C;&#x5219;&#x4E0D;&#x518D;&#x8FDB;&#x884C;&#x5F80;&#x540E;&#x8F6C;&#x6362;&#xFF0C;&#x8FD4;&#x56DE;&#x5DF2;&#x7ECF;&#x8F6C;&#x597D;&#x7684;&#x90E8;&#x5206;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;3.14more non-digit characters&apos;</span>) <span class="hljs-comment">// 3.14</span>
</code></pre>
<p><code>parseFloat</code>&#x65B9;&#x6CD5;&#x4F1A;&#x81EA;&#x52A8;&#x8FC7;&#x6EE4;&#x5B57;&#x7B26;&#x4E32;&#x524D;&#x5BFC;&#x7684;&#x7A7A;&#x683C;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;\t\v\r12.34\n &apos;</span>) <span class="hljs-comment">// 12.34</span>
</code></pre>
<p>&#x5982;&#x679C;&#x53C2;&#x6570;&#x4E0D;&#x662F;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x6216;&#x8005;&#x5B57;&#x7B26;&#x4E32;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E0D;&#x80FD;&#x8F6C;&#x5316;&#x4E3A;&#x6D6E;&#x70B9;&#x6570;&#xFF0C;&#x5219;&#x8FD4;&#x56DE;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseFloat</span>([]) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;FF2&apos;</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;&apos;</span>) <span class="hljs-comment">// NaN</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5C24;&#x5176;&#x503C;&#x5F97;&#x6CE8;&#x610F;&#xFF0C;<code>parseFloat</code>&#x4F1A;&#x5C06;&#x7A7A;&#x5B57;&#x7B26;&#x4E32;&#x8F6C;&#x4E3A;<code>NaN</code>&#x3002;</p>
<p>&#x8FD9;&#x4E9B;&#x7279;&#x70B9;&#x4F7F;&#x5F97;<code>parseFloat</code>&#x7684;&#x8F6C;&#x6362;&#x7ED3;&#x679C;&#x4E0D;&#x540C;&#x4E8E;<code>Number</code>&#x51FD;&#x6570;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">parseFloat</span>(<span class="hljs-literal">true</span>)  <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">Number</span>(<span class="hljs-literal">true</span>) <span class="hljs-comment">// 1</span>

<span class="hljs-built_in">parseFloat</span>(<span class="hljs-literal">null</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">Number</span>(<span class="hljs-literal">null</span>) <span class="hljs-comment">// 0</span>

<span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;&apos;</span>) <span class="hljs-comment">// NaN</span>
<span class="hljs-built_in">Number</span>(<span class="hljs-string">&apos;&apos;</span>) <span class="hljs-comment">// 0</span>

<span class="hljs-built_in">parseFloat</span>(<span class="hljs-string">&apos;123.45#&apos;</span>) <span class="hljs-comment">// 123.45</span>
<span class="hljs-built_in">Number</span>(<span class="hljs-string">&apos;123.45#&apos;</span>) <span class="hljs-comment">// NaN</span>
</code></pre>
<h3 id="isnan">isNaN()</h3>
<p><code>isNaN</code>&#x65B9;&#x6CD5;&#x53EF;&#x4EE5;&#x7528;&#x6765;&#x5224;&#x65AD;&#x4E00;&#x4E2A;&#x503C;&#x662F;&#x5426;&#x4E3A;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">isNaN</span>(<span class="hljs-literal">NaN</span>) <span class="hljs-comment">// true</span>
<span class="hljs-built_in">isNaN</span>(<span class="hljs-number">123</span>) <span class="hljs-comment">// false</span>
</code></pre>
<p>&#x4F46;&#x662F;&#xFF0C;<code>isNaN</code>&#x53EA;&#x5BF9;&#x6570;&#x503C;&#x6709;&#x6548;&#xFF0C;&#x5982;&#x679C;&#x4F20;&#x5165;&#x5176;&#x4ED6;&#x503C;&#xFF0C;&#x4F1A;&#x88AB;&#x5148;&#x8F6C;&#x6210;&#x6570;&#x503C;&#x3002;&#x6BD4;&#x5982;&#xFF0C;&#x4F20;&#x5165;&#x5B57;&#x7B26;&#x4E32;&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x5B57;&#x7B26;&#x4E32;&#x4F1A;&#x88AB;&#x5148;&#x8F6C;&#x6210;<code>NaN</code>&#xFF0C;&#x6240;&#x4EE5;&#x6700;&#x540E;&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x8FD9;&#x4E00;&#x70B9;&#x8981;&#x7279;&#x522B;&#x5F15;&#x8D77;&#x6CE8;&#x610F;&#x3002;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;<code>isNaN</code>&#x4E3A;<code>true</code>&#x7684;&#x503C;&#xFF0C;&#x6709;&#x53EF;&#x80FD;&#x4E0D;&#x662F;<code>NaN</code>&#xFF0C;&#x800C;&#x662F;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E32;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">isNaN</span>(<span class="hljs-string">&apos;Hello&apos;</span>) <span class="hljs-comment">// true</span>
<span class="hljs-comment">// &#x76F8;&#x5F53;&#x4E8E;</span>
<span class="hljs-built_in">isNaN</span>(<span class="hljs-built_in">Number</span>(<span class="hljs-string">&apos;Hello&apos;</span>)) <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x51FA;&#x4E8E;&#x540C;&#x6837;&#x7684;&#x539F;&#x56E0;&#xFF0C;&#x5BF9;&#x4E8E;&#x5BF9;&#x8C61;&#x548C;&#x6570;&#x7EC4;&#xFF0C;<code>isNaN</code>&#x4E5F;&#x8FD4;&#x56DE;<code>true</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">isNaN</span>({}) <span class="hljs-comment">// true</span>
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">isNaN</span>(<span class="hljs-built_in">Number</span>({})) <span class="hljs-comment">// true</span>

<span class="hljs-built_in">isNaN</span>([<span class="hljs-string">&apos;xzy&apos;</span>]) <span class="hljs-comment">// true</span>
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-built_in">isNaN</span>(<span class="hljs-built_in">Number</span>([<span class="hljs-string">&apos;xzy&apos;</span>])) <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x4F46;&#x662F;&#xFF0C;&#x5BF9;&#x4E8E;&#x7A7A;&#x6570;&#x7EC4;&#x548C;&#x53EA;&#x6709;&#x4E00;&#x4E2A;&#x6570;&#x503C;&#x6210;&#x5458;&#x7684;&#x6570;&#x7EC4;&#xFF0C;<code>isNaN</code>&#x8FD4;&#x56DE;<code>false</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">isNaN</span>([]) <span class="hljs-comment">// false</span>
<span class="hljs-built_in">isNaN</span>([<span class="hljs-number">123</span>]) <span class="hljs-comment">// false</span>
<span class="hljs-built_in">isNaN</span>([<span class="hljs-string">&apos;123&apos;</span>]) <span class="hljs-comment">// false</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E4B;&#x6240;&#x4EE5;&#x8FD4;&#x56DE;<code>false</code>&#xFF0C;&#x539F;&#x56E0;&#x662F;&#x8FD9;&#x4E9B;&#x6570;&#x7EC4;&#x80FD;&#x88AB;<code>Number</code>&#x51FD;&#x6570;&#x8F6C;&#x6210;&#x6570;&#x503C;&#xFF0C;&#x8BF7;&#x53C2;&#x89C1;&#x300A;&#x6570;&#x636E;&#x7C7B;&#x578B;&#x8F6C;&#x6362;&#x300B;&#x4E00;&#x7AE0;&#x3002;</p>
<p>&#x56E0;&#x6B64;&#xFF0C;&#x4F7F;&#x7528;<code>isNaN</code>&#x4E4B;&#x524D;&#xFF0C;&#x6700;&#x597D;&#x5224;&#x65AD;&#x4E00;&#x4E0B;&#x6570;&#x636E;&#x7C7B;&#x578B;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">myIsNaN</span>(<span class="hljs-params">value</span>) </span>{
  <span class="hljs-keyword">return</span> <span class="hljs-keyword">typeof</span> value === <span class="hljs-string">&apos;number&apos;</span> &amp;&amp; <span class="hljs-built_in">isNaN</span>(value);
}
</code></pre>
<p>&#x5224;&#x65AD;<code>NaN</code>&#x66F4;&#x53EF;&#x9760;&#x7684;&#x65B9;&#x6CD5;&#x662F;&#xFF0C;&#x5229;&#x7528;<code>NaN</code>&#x4E3A;&#x552F;&#x4E00;&#x4E0D;&#x7B49;&#x4E8E;&#x81EA;&#x8EAB;&#x7684;&#x503C;&#x7684;&#x8FD9;&#x4E2A;&#x7279;&#x70B9;&#xFF0C;&#x8FDB;&#x884C;&#x5224;&#x65AD;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">myIsNaN</span>(<span class="hljs-params">value</span>) </span>{
  <span class="hljs-keyword">return</span> value !== value;
}
</code></pre>
<h3 id="isfinite">isFinite()</h3>
<p><code>isFinite</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x5E03;&#x5C14;&#x503C;&#xFF0C;&#x8868;&#x793A;&#x67D0;&#x4E2A;&#x503C;&#x662F;&#x5426;&#x4E3A;&#x6B63;&#x5E38;&#x7684;&#x6570;&#x503C;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">isFinite</span>(<span class="hljs-literal">Infinity</span>) <span class="hljs-comment">// false</span>
<span class="hljs-built_in">isFinite</span>(-<span class="hljs-literal">Infinity</span>) <span class="hljs-comment">// false</span>
<span class="hljs-built_in">isFinite</span>(<span class="hljs-literal">NaN</span>) <span class="hljs-comment">// false</span>
<span class="hljs-built_in">isFinite</span>(<span class="hljs-literal">undefined</span>) <span class="hljs-comment">// false</span>
<span class="hljs-built_in">isFinite</span>(<span class="hljs-literal">null</span>) <span class="hljs-comment">// true</span>
<span class="hljs-built_in">isFinite</span>(<span class="hljs-number">-1</span>) <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x9664;&#x4E86;<code>Infinity</code>&#x3001;<code>-Infinity</code>&#x3001;<code>NaN</code>&#x548C;<code>undefined</code>&#x8FD9;&#x51E0;&#x4E2A;&#x503C;&#x4F1A;&#x8FD4;&#x56DE;<code>false</code>&#xFF0C;<code>isFinite</code>&#x5BF9;&#x4E8E;&#x5176;&#x4ED6;&#x7684;&#x6570;&#x503C;&#x90FD;&#x4F1A;&#x8FD4;&#x56DE;<code>true</code>&#x3002;</p>
<h2 id="&#x53C2;&#x8003;&#x94FE;&#x63A5;">&#x53C2;&#x8003;&#x94FE;&#x63A5;</h2>
<ul>
<li>Dr. Axel Rauschmayer, <a href="http://www.2ality.com/2012/04/number-encoding.html" target="_blank" rel="nofollow">How numbers are encoded in JavaScript</a></li>
<li>Humphry, <a href="http://blog.segmentfault.com/humphry/1190000000407658" target="_blank" rel="nofollow">JavaScript &#x4E2D; Number &#x7684;&#x4E00;&#x4E9B;&#x8868;&#x793A;&#x4E0A;/&#x4E0B;&#x9650;</a></li>
</ul>




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